The user can insert a series of single points (single vowels) or glides.
The vowels can be long or not
Rounded vowels are marked with a different color, or maybe circled. And/or unrounded vowels appear to the left of a mark, and rounded vowels appear to the right of it.
The points for vowels or glides may be tagged with the default IPA symbol, or with a custom tag.
The a state of the diagram must be sharable e.g. any parameters should appear as URL parameters.
